Gas turbine engine integrated heat exchanger

ABSTRACT

A heat exchanger apparatus including at least one cooling channel formed within and about an engine booster lip or an engine nacelle and configured to receive a flow of a circulating working fluid; and at least one fluid port communicating with the at least one cooling channel and an exterior of the engine booster lip or the engine nacelle.

BACKGROUND

This invention relates generally to turbomachines, and more particularlyto the design of an enhanced heat exchanger, in the form of anair-cooled surface cooler, for use in turbomachines.

Modern turbofan/turbojet engines have an ever-increasing demand ofcooling, including gearbox oil, cooling air and electronics, while atthe same time their efficiency has to be pushed ever higher. Currentlyair-cooled oil coolers are usually plate-fin type “brick” heatexchangers that are mounted within the bypass channel to receive flowfrom the engine intake or bypass stream or from a separate air-intake inthe nacelle or fan casing. New designs have mitigated the high drag ofthis design due to the plate-fin exchanger sitting in the bypass channelby utilizing a surface cooler that is mounted flush with the aft fancowling. However, the space in this region of the engine is limited andcurrent designs utilize nearly all the available space. As a result,newer engine technologies, which have more heat that must be dissipated,will be thermally constrained due to the lack of space available ontowhich the cooler may be formed. In addition, current heat exchangerssuch as these plate-fin “brick” coolers obstruct the air flow and incuraerodynamic losses as the cooling requirements grow. These losses meanincreased specific fuel consumption.

By using a surface cooler where only the cooler fins project into theengine air bypass flow, the drag of the oil cooler heat exchanger hasbeen reduced over that of a traditional plate-fin cooler. Howeverincreasing heat loads requires that the surface cooler will need to belarger in size. Aircraft weight is a current concern in the currentindustry, with a decrease in aircraft weight resulting in an efficiencyincrease. In addition, new engines are becoming space constrained,making the size and weight of these types of plate-fin coolersprohibitive.

Prior attempts to overcome this problem have utilized a coil of tubingwithin the outlet guide vane/strut and in thermal contact with thesurface of the strut. As oil is flowed through the tubing heat istransferred to the bypass air stream through the strut skin. Inaddition, systems that utilize various air scoops in the fan bypassflow, thereby directing air through a plate-fin heat exchanger have beenutilized, as well as the use of actuators to push the plate-fin heatexchange in and out of the fan bypass flow or alternatively block partof the air scoop. By modulating the amount of air utilized by the heatexchanger only the minimal amount of airflow required is utilized. Whileresulting in the cooling of oil, as well as additional aircraftcomponents, these systems may be thermally limited, cost prohibitive tofabricate and implement an increase drag on the aircraft.

In an attempt to increase efficiency of these known surface coolers,there is a desire for an improved air cooled oil cooler that will enablethe cooler to be implemented into newer engine technologies withincreased heat dissipation requirements, while remaining cost effectiveand having minimal aerodynamic drag as compared to current designs, andtherefore provide an overall more efficient system.

BRIEF SUMMARY

These and other shortcomings of the prior art are addressed by thepresent disclosure, which provides a heat exchanger apparatus.

In accordance with an embodiment, provided is a heat exchanger apparatusincluding at least one cooling channel formed within and about an enginebooster lip or an engine annular fan casing and configured to receive aflow of a circulating working fluid; and at least one fluid portcommunicating with the at least one cooling channel and an exterior ofthe engine booster lip or the engine annular fan casing.

In accordance with another embodiment, provided is a heat exchangerapparatus including a plurality of cooling channels integrally formedwithin and about at least a portion of a circumference of one of anengine booster lip or an engine nacelle and wherein each of theplurality of cooling channels is configured to receive a flow ofcirculating working fluid; and inlet and outlet ports communicating withthe at least one cooling channel and an exterior of the engine boosterlip or the engine nacelle.

In accordance with yet another embodiment, provided is and engineincluding a core engine; and a heat exchanger apparatus. The heatexchanger apparatus including at least one cooling channel integrallyformed within and about an engine booster lip or an engine annular fancasing and configured to receive a flow of a circulating working fluid;and at least one fluid port communicating with the at least one flushmounted cooling channel and an exterior of the engine booster lip or theengine annular fan casing. The at least one cooling channel isconfigured to provide an increase in the heat transfer coefficient ofthe heat exchanger apparatus while minimizing aerodynamic losses andspecific fuel consumption (SFC).

Other objects and advantages of the present disclosure will becomeapparent upon reading the following detailed description and theappended claims with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

The above and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic cross-sectional view of a gas turbine engineincorporating a heat exchanger system constructed according to an aspectof the present disclosure;

FIG. 2 is an enlarged view of a portion of the gas turbine engine ofFIG. 1;

FIG. 3 is a side view of an outlet guide vane and a portion of a boosterlip in contact with a root of the outlet guide vane constructed inaccordance with an aspect of the present disclosure;

FIG. 4 is a perspective view of a portion of the gas turbine engine ofFIG. 1 illustrating the booster lip and associated outlet guide vanes;

FIG. 5 a schematic cross-sectional view of a gas turbine engineincorporating a heat exchanger system constructed according to anotheraspect of the present disclosure;

FIG. 6 is an enlarged view of a portion of the gas turbine engine ofFIG. 5; and

FIG. 7 is a perspective view of an exterior of the gas turbine engine ofFIG. 5.

DETAILED DESCRIPTION

The invention will be described for the purposes of illustration only inconnection with certain embodiments; however, it is to be understoodthat other objects and advantages of the present disclosure will be madeapparent by the following description of the drawings according to thedisclosure. While preferred embodiments are disclosed, they are notintended to be limiting. Rather, the general principles set forth hereinare considered to be merely illustrative of the scope of the presentdisclosure and it is to be further understood that numerous changes maybe made without straying from the scope of the present disclosure.

Embodiments disclosed herein relate to heat exchangers and moreparticularly to enhanced heat exchangers for use in an engine such as anaircraft engine. The exemplary heat exchangers may be used for providingefficient cooling. Further, the term “heat exchangers” as used hereinmay be used interchangeably with the term “surface coolers”. As usedherein, the heat exchangers/surface coolers are applicable to varioustypes of turbomachinery applications such as, but not limited to,turbojets, turbo fans, turbo propulsion engines, aircraft engines, gasturbines, steam turbines, wind turbines, and water turbines.

Preferred embodiments of the present disclosure are illustrated in thefigures with like numerals being used to refer to like and correspondingparts of the various drawings. It is also understood that terms such as“top”, “bottom”, “outward”, “inward”, and the like are words ofconvenience and are not to be construed as limiting terms. It is to benoted that the terms “first,” “second,” and the like, as used herein donot denote any order, quantity, or importance, but rather are used todistinguish one element from another. The terms “a” and “an” do notdenote a limitation of quantity, but rather denote the presence of atleast one of the referenced item. The modifier “about” used inconnection with a quantity is inclusive of the stated value and has themeaning dictated by the context (e.g., includes the degree of errorassociated with measurement of the particular quantity).

Referring to the drawings wherein identical reference numerals denotethe same elements throughout the various views, FIGS. 1 and 2 depictschematic illustrations of an exemplary aircraft engine assembly 10 inaccordance with the present disclosure. It is noted that the portion ofthe engine assembly 10 illustrated in FIG. 2 is indicated by dotted linein FIG. 1. The engine assembly 10 has a longitudinal center line or axis12 and an outer stationary annular casing 14 disposed concentricallyabout and coaxially along the axis 12. In the exemplary embodiment, theengine assembly 10 includes a fan assembly 16, a booster compressor 18,a core gas turbine engine 20, and a low-pressure turbine 22 that may becoupled to the fan assembly 16 and the booster compressor 18. The fanassembly 16 includes a plurality of rotor fan blades 24 that extendsubstantially radially outward from a fan rotor disk 26, as well as aplurality of structural strut members 28 and outlet guide vanes (“OGVs”)29 that may be positioned downstream of the rotor fan blades 24. In thisexample, separate members are provided for the aerodynamic andstructural functions. In other configurations, each of the OGVs 29 maybe both an aero-turning element and a structural support for an annularfan casing (described presently). While the concepts of the presentdisclosure will be described using the outlet guide vane 29 as anexample of a portion of the heat exchanger apparatus, it will beunderstood that those concepts are applicable to any aero-turning orstationary airfoil-type structure within the engine assembly 10.

The core gas turbine engine 20 includes a high-pressure compressor 30, acombustor 32, and a high-pressure turbine 34. The booster compressor 18includes a plurality of rotor blades 36 that extend substantiallyradially outward from a compressor rotor disk 38 coupled to a firstdrive shaft 40. The high-pressure compressor 30 and the high-pressureturbine 34 are coupled together by a second drive shaft 42. The firstand second drive shafts 40 and 42 are rotatably mounted in bearings 43which are themselves mounted in a fan frame 45 and a turbine rear frame47. The fan frame 45 has a central hub 49 connected to the annular fancasing 51. The engine assembly 10 also includes an intake side 44, acore engine exhaust side 46, and a fan exhaust side 48.

During operation, the fan assembly 14 compresses air entering the engineassembly 10 through the intake side 44. The airflow exiting the fanassembly 14 is split such that a portion 50 of the airflow is channeledinto the booster compressor 18, as compressed airflow, and a remainingportion 52 of the airflow bypasses the booster compressor 18 and thecore gas turbine engine 20 and exits the engine assembly 10 through thefan exhaust side 48 as bypass air. This bypass air portion 52 flows pastand interacts with the structural strut members 28 and the outlet guidevanes 29 creating unsteady pressures on the stator surfaces as well asin the surrounding airflow that radiate as acoustic waves. The pluralityof rotor blades 24 compress and deliver the compressed airflow 50towards the core gas turbine engine 20. Furthermore, the airflow 50 isfurther compressed by the high-pressure compressor 30 and is deliveredto the combustor 32. Moreover, the compressed airflow 50 from thecombustor 32 drives the rotating high-pressure turbine 34 and thelow-pressure turbine 22 and exits the engine assembly 10 through thecore engine exhaust side 46.

As previously noted, in certain presently available commercial enginesheat exchangers are employed. Furthermore, high heat loads may lead tosub-optimal performance of certain heat exchangers. In accordance withexemplary aspects of the present technique, an apparatus 54 configuredto function as a heat exchanger is presented. More particularly, theexemplary apparatus 54 may be configured to address the heat exchangerequirements of a turbomachine such as an aircraft engine, for example.Hereinafter, the term “heat exchanger” may be used to refer to theapparatus 54 configured to facilitate cooling of the turbomachine.

In an embodiment, the booster compressor 18 and some or all of thestructural fan outlet struts 28 in the engine assembly 10 comprise aportion of a heat exchanger integrated into their structures. In anotherembodiment, the booster compressor 18 and some or all of the OGVs 29 inthe engine assembly 10 comprise a portion of a heat exchanger integratedinto their structures. In yet another embodiment, the booster compressor18 and some or all of the structural fan outlet struts 28 and the OGVs29 in the engine assembly 10 comprise a portion of a heat exchangerintegrated into their structures.

Referring now to FIG. 3, illustrated is one of the OGVs 29 of the engineassembly 10, illustrated in more detail. In general, the OGV 29comprises an airfoil 60 having a leading edge 62, a trailing edge 64, atip 66 and a root 68. An arcuate inner platform 70 is disposed at theroot 68 of the airfoil 60.

The airfoil 60 is assembled from a body (not shown) and a cover 72. Thebody and the cover 72 are both made from a material with suitablestrength and weight characteristics for the intended application. Inaddition, illustrated in FIG. 3 is an interior wall 74 of a booster lip76 of the booster compressor 18, illustrating at least one coolingchannel 78 integrally formed within and about the engine booster lip 76and in contact with the root 68 of the OGVs 29. In an embodiment, thebooster lip 76 includes a plurality of cooling channels 78 formedtherein.

Referring specifically to FIG. 4, at least one cooling channel 78provides a space within the booster lip 76 for a flow of working fluid,for example lubrication oil. In an embodiment, the at least one coolingchannel 78 is integral to the booster lip, or in other words, the atleast one cooling channel 78 is defined by the structure of the boosterlip 76 itself, rather than any intermediate structure, such as fillermaterials. In an alternate embodiment, the at least one cooling channel78 is defined by extruded channels, tubes, or piping that are embeddedwithin the structure of the booster lip 76.

In operation, the working fluid is in intimate contact with the root 68of the OGV 29 via the at least one cooling channel 78. This results inthe airfoil 60 of the OGV 29 acting as a cooling fm for the workingfluid in the at least one cooling channel 78 on the booster compressorcircumference, maximizing the heat transfer rate. The interior of the atleast one cooling channel 78, i.e. its size, shape, surface texture, andarrangement of internal walls or other features, may be configured tomaximize heat transfer between the working fluid and the OGV 29,minimize pressure loses, and so forth. As used herein the term “channel”refers to the entire volume available for flow of working fluid withinthe booster lip 76, regardless of whether it is configured as a singlecooling channel or a plurality of cooling channels.

As shown in FIGS. 3 and 4, the at least one cooling channel 78 isconfigured as a plurality of parallel channels 79 running in a generallyradial (i.e. spanwise) direction and separated by walls or ribs. In anembodiment, the channels 79 are arranged into “groups” 80, aneight-channel group arrangement being shown, providing working fluidcommunication with a single OGV 29. Cross-passages (not shown) mayinterconnect the groups 80 to define a continuous flow pathcircumferentially about the booster compressor 18, and more particularlythe booster lip 76. In an embodiment, the cross-passages are configuredto provide for a flow of the working fluid about at least a portion ofthe circumference of the booster lip 76. In another embodiment, thecross-passages are configured to provide for a flow of the working fluidabout a complete circumference of the booster lip 76. The at least onecooling channel 78 may be formed, for example, by a machining process.In the illustrated example, the width of each of the plurality ofparallel channels 79 is approximately 6.4 mm (0.25 in.).

Referring now to FIGS. 5-7, illustrated is another embodiment of anengine assembly including a heat exchanger apparatus according to thisdisclosure. FIGS. 5 and 6 depict schematic illustrations of an exemplaryaircraft engine assembly 80, generally similar to aircraft engineassembly 10 of FIGS. 1-2, in accordance with the present disclosure.

As previously noted, in certain presently available commercial enginesheat exchangers are employed. In accordance with exemplary aspects ofthe present technique, an apparatus 82 configured to function as a heatexchanger is presented. More particularly, the apparatus 82 may beconfigured to address the heat exchange requirements of a turbomachinesuch as an aircraft engine, for example. Hereinafter, the term “heatexchanger” may be used to refer to the apparatus 82 configured tofacilitate cooling of the turbomachine. In the embodiment illustrated inFIGS. 5-7, the heat exchanger apparatus 82 may be comprised of at leastone cooling channel 84 disposed within and about an engine nacelle, alsoreferred to herein interchangeably as the annular fan casing, 51 andconfigured to receive a flow of a circulating working fluid therein.

In the embodiment illustrated in FIGS. 5-7, a plurality of coolingchannels 84 are formed at least partially about a circumference of theannular fan casing 51 and in thermal contact with a thermal plate 86 onthe annular fan casing 51. In an embodiment, the thermal plate 86 iscomprised of any metal or composite material capable of conducting heat.The plurality of channels 84 are configured to aid in cooling a workingfluid that may be heated by various parts of the engine assembly 80. Aswill be appreciated, the working fluid may be heated by parts of theengine assembly 80 such as bearings. The heated fluid is channeledthrough the heat exchanger 82 via the plurality of channels 84. The heatfrom the fluid may be transferred from the walls of the plurality ofchannels 84 and dissipated into the thermal plate 86 and surroundingambient air surrounding the annular fan casing 51, or nacelle structure.In an embodiment, this fluid may then be carried back to the parts inengine assembly 80.

FIG. 7 illustrates a perspective view of a portion of the exemplary heatexchanger apparatus 82 with the thermal plate 86 on an outer surface ofthe annular fan casing 51. In an embodiment, the thermal plate 86 may beintegrally formed, or mounted flush to the annular fan casing 51 so asto provide minimal to no effect on the engine aerodynamics In theillustrated embodiment, the heat exchanger 82 operates without the needfor a fin structures, relying on movement of the airflow over the enginefan casing 51, and thus the thermal plate 86, to provide dissipation ofthe heat. At high altitudes, the heat exchanger 82 operates extremelyefficiently due to the large temperature differential between theworking fluid and the ambient air passing over the engine fan casing 51.

In operation, hot working fluid from the engine (e.g. lubricating oil oraccessory cooling oil) is ported via at least one inlet and outlet port90 (FIG. 1) communicating with the at least one cooling channel 78, 84and an exterior of the engine booster lip 76 or the annular fan casing51. The working fluid flows through the at least one cooling channel 78,84 where heat is removed from the fluid by transfer to the airflowsurrounding the OGV (in this case fan bypass flow) 29 (FIG. 1) or theengine fan casing 51 (FIG. 5). The heated oil then passes back to theremainder of the oil system. It will be understood that the oil systemincorporates pumps, filters, lines, valves, tanks, and other equipmentas needed to provide a flow of pressurized oil. Such components arewell-known and therefore not illustrated here.

Using the concepts described herein, existing turbine engine structures,such as the booster compressor in combination with the OGVs orstructural struts, or an engine fan casing may incorporate an oilcooling function, in addition to aero-turning and/or structuralfunctions. The oil cooling function is performed utilizing exitingengine structures, without the need for the addition of a traditionalplate-and-fin heat exchanger.

This concept has several advantages. Among them are minimal aerodynamiclosses, as well as providing an increase in volume flow and propulsionpower by permitting any heat that is added to the bypass flow after thefan, to be retained. A significant improvement in specific fuelconsumption (“SFC”) is expected as well.

The foregoing has described a heat exchanger for a gas turbine engineand a method for its operation. While the present disclosure has beendescribed with respect to a limited number of embodiments, those skilledin the art, having benefit of this disclosure, will appreciate thatother embodiments may be devised which do not depart from the scope ofthe disclosure as described herein. While the present disclosure hasbeen described with reference to exemplary embodiments, it will beunderstood by those skilled in the art that various changes may be madeand equivalents may be substituted for elements thereof withoutdeparting from the scope of the disclosure. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present disclosure without departing from theessential scope thereof. Therefore, it is intended that the presentdisclosure not be limited to the particular embodiment disclosed as thebest mode contemplated for carrying out the disclosure. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the disclosure.

What is claimed is:
 1. A heat exchanger apparatus comprising: at leastone cooling channel formed within and about an engine booster lip or anengine annular fan casing and configured to receive a flow of acirculating working fluid; and at least one fluid port communicatingwith the at least one cooling channel and an exterior of the enginebooster lip or the engine annular fan casing.
 2. The heat exchangerapparatus of claim 1, wherein the at least one cooling channel isembedded within the booster lip and in thermal contact with a root of atleast one fan outlet guide vane or fan outlet strut.
 3. The heatexchanger apparatus of claim 2, wherein a plurality of cooling channelsare embedded within and about the booster lip and wherein each of theplurality of cooling channels is in thermal contact with the root of atleast one fan outlet guide vane or fan outlet strut.
 4. The heatexchanger apparatus of claim 2, wherein the at least one cooling channelis configured about at least a portion of a circumference of the enginebooster lip.
 5. The heat exchanger apparatus of claim 4, wherein the atleast one cooling channel is configured about a complete circumferenceof the engine booster lip.
 6. The heat exchanger apparatus of claim 1,wherein the at least one cooling channel is embedded within and aboutthe engine annular fan casing and in thermal contact with a thermalplate on an outer surface of the engine annular fan casing.
 7. The heatexchanger apparatus of claim 6, wherein the thermal plate is flushmounted to the outer surface of the engine annular fan casing.
 8. Theheat exchanger apparatus of claim 6, wherein the thermal plate isintegrally formed with the outer surface of the engine annular fancasing.
 9. The heat exchanger apparatus of claim 6, wherein a pluralityof cooling channels are embedded within and about the engine annular fancasing and wherein each of the plurality of cooling channels is inthermal contact with the thermal plate.
 10. The heat exchanger apparatusof claim 6, wherein the at least one cooling channel is configured aboutat least a portion of a circumference of the engine annular fan casing.11. The heat exchanger apparatus of claim 10, wherein the at least onecooling channel is configured about a complete circumference of theengine annular fan casing.
 12. A heat exchanger apparatus comprising: aplurality of cooling channels integrally formed within and about atleast a portion of a circumference of one of an engine booster lip or anengine nacelle and wherein each of the plurality of cooling channels isconfigured to receive a flow of circulating working fluid; and inlet andoutlet ports communicating with the at least one cooling channel and anexterior of the engine booster lip or the engine nacelle.
 13. The heatexchanger apparatus of claim 12, wherein the plurality of coolingchannels comprises a plurality of channels oriented circumferentiallyabout the one an engine booster lip or an engine nacelle.
 14. The heatexchanger apparatus of claim 13, wherein each of the plurality ofcooling channels is embedded within the booster lip and in thermalcontact with a base of at least one fan outlet guide vane or fan outletstrut.
 15. The heat exchanger apparatus of claim 13, wherein theplurality of cooling channels are configured about at least a portion ofa circumference of the engine booster lip.
 16. The heat exchangerapparatus of claim 13, wherein each of the plurality of cooling channelsis embedded within and about at least a portion of a circumference ofthe engine nacelle and in thermal contact with a thermal plate on anouter surface of the engine nacelle.
 17. The heat exchanger apparatus ofclaim 16, wherein the thermal plate is one of mounted to the outersurface of the engine nacelle or integrally formed with the outersurface of the engine nacelle.
 18. An engine comprising: a core engine;and a heat exchanger apparatus comprising: at least one cooling channelintegrally formed within and about an engine booster lip or an engineannular fan casing and configured to receive a flow of a circulatingworking fluid; and at least one fluid port communicating with the atleast one flush mounted cooling channel and an exterior of the enginebooster lip or the engine annular fan casing, wherein the at least onecooling channel is configured to provide an increase in the heattransfer coefficient of the heat exchanger apparatus while minimizingaerodynamic losses and specific fuel consumption (SFC).
 19. The engineof claim 18, wherein the at least one cooling channel is configuredabout at least a portion of a circumference of the engine booster lip.20. The engine of claim 18, wherein at least one cooling channel isembedded within and about the engine annular fan casing and in thermalcontact with a thermal plate on an outer surface of the engine annularfan casing.